hi all im am new to the forum and need some advice with my nad 701 amp, i bought it two weeks ago and it worked fine when all plugged in, i turned it back on 2 days later and very low distorted sound and it switched into a protection mode, i have had a read around and replaced the four big metal transistors mj2955 & 2n3055 and acouple of others b649a &d669a as they were getting hot and its still the same but now the sound is louder but still distorted and the amp now stays on, do i need to add the resistors which people say to do in a thread on here and could someone please say what resistors i need and where to solder them thanks for any help, also does this amp have mute transistors and how can I locate them to test thanks in advance

Last edited by sirius1967; 12th July 2015 at 09:58 PM.
Reason: Adding a question

Hi all I am new to the forum and need some advice with my NAD 701 amp.

I bought it two weeks ago and it worked fine when all plugged in, i turned it back on 2 days later and very low distorted sound and it switched into a protection mode.

I have had a read around and replaced the four big metal transistors mj2955 & 2n3055 and acouple of others b649a &d669a as they were getting hot and its still the same but now the sound is louder but still distorted and the amp now stays on.

Do i need to add the resistors which people say to do in a thread on here and could someone please say what resistors i need and where to solder them thanks for any help, also does this amp have mute transistors and how can I locate them to test thanks in advance

yes i have the shematic 701 i found it on here, i have used it to order exact replacement parts, im still waiting for some transistors to get here before i can go any further, up to now i have changed all the .1uf caps 180ohm resistors 100ohm resistors mj2955 & 2n3055 and still need to change 4amp fuses, can i replace the 6800 caps with 10,000 to improve sound ?, thanks for your reply

If this amp is as old as I think it is, and if it sat un-used for a long period, any electrolytic or tantalum caps could be bad. In the NAD preamp I have, the push button switches got dirty over time and became intermittant, causing a very loud hum...

Hi sorry, all but one fuse is blown, after testing transistors q415,q417,q418,q416,q411,q409q413 (split in two) q414,q410,q412, q407 and 408 around half was damaged, resistor 453 was fried other resistors seem ok ? Tested loads out of circuit, l am just waiting for some parts to arrive then I will change them, thanks for the replies

I no what the symbols mean, diode capacitor ect my problem is the actual board layout is so different I get lost with it so I have been ordering parts and changing them, all the .1uf caps are swollen so I've changed them along with a few other bits for now, so till I have them all I'm stuck, thanks for your reply